城市化
分水岭
环境科学
水资源管理
大都市区
地理
中国
水文学(农业)
地质学
经济增长
计算机科学
机器学习
经济
考古
岩土工程
作者
Yixin He,Xiaofeng Wang,Huai Chen,Xingzhong Yuan,Ning Wu,Yuewei Zhang,Junsheng Yue,Qiaoyong Zhang,Yuanbin Diao,Lei Zhou
标识
DOI:10.1016/j.atmosenv.2017.09.043
摘要
Abstract Watershed urbanization, an integrated anthropogenic perturbation, is another considerable global concern in addition to that of global warming and may significantly enrich the N loadings of watersheds, which then greatly influences the nitrous oxide (N 2 O) production and fluxes of these aquatic systems. However, little is known about the N 2 O dynamics in human-dominated metropolitan river networks. In this study, we present the temporal and spatial variations in N 2 O saturation and emission in the Chongqing metropolitan river network, which is undergoing intensified urbanization. The N 2 O saturation and fluxes at 84 sampling sites ranged from 126% to 10536% and from 4.5 to 1566.8 μmol N 2 O m −2 d −1 , with means of 1780% and 261 μmol N 2 O m −2 d −1 . The riverine N 2 O saturation and fluxes increased along with the urbanization gradient and urbanization rate, with disproportionately higher values in urban rivers due to the N 2 O-rich sewage inputs and enriched in situ N substrates. We found a clear seasonal pattern of N 2 O saturation, which was co-regulated by both water temperature and precipitation. Regression analysis indicated that the N substrates and dissolved oxygen (DO) that controlled nitrogen metabolism acted as good predictors of the N 2 O emissions of urban river networks. Particularly, phosphorus (P) and hydromorphological factors (water velocity, river size and bottom substrate) had stronger relationships with the N 2 O saturation and could also be used to predict the N 2 O emission hotspots in regions with rapid urbanization. In addition, the default emission factors ( EF5-r ) used in the Intergovernmental Panel on Climate Change (IPCC) methodology may need revision given the differences among the physical and chemical factors in different rivers, especially urban rivers.
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